Commons talk:GNU Free Documentation License, version 1.2

Could some-one please explain in simple English what " Invariant Sections, ... Front-Cover Texts, and ... Back-Cover Texts" mean(s)?Kdammers (talk) 10:02, 20 January 2013 (UTC)
I am a teacher. I want to use images under the GNU license in my presentattions. Does it suffice to attribute the author, or do i have to list all the past histry of the image? please respond.